Dental appliances such as false teeth and bridges have become more commonplace as the number of senior citizens increases, as such appliances become more affordable, and as concern with personal appearance increases. The fabrication of dental appliances by either a dentist or technician has been simplified with the advent of plastic teeth, while bridge supports have facilitated the accurate reconstruction of teeth configurations. While the structural integrity and useful lifetime of such dental appliances are of the utmost importance, the appearance and aesthetics of such structures are also of considerable importance to most users and potential users. Increasingly the cost and time involved in reconstructing a patient's teeth are devoted to aesthetics considerations such as the color, shade and other characteristics of the artificial teeth in the dental appliance. The goal is, of course, to match the newly installed artificial teeth in shade and hue as closely as possible with the patient's remaining teeth and to provide a most natural appearance for the user. It is also desirable, once the proper hue is determined to provide a progressively darker shade in the same hue, where multiple teeth are needed and the replacement teeth are to be located toward the rear of the mouth.
The dentist's first task is to prepare the patient's mouth in order to fabricate the dental appliance, commonly referred to as "dentures" such as a partial, a crown, a bridge, veneers, laminates, or over dentures. With the patient's mouth prepared, an impression of the patient's mouth is then obtained. The dentist must then determine the shade and color, or hue, of any artificial teeth in the dental appliance.
Shade matching or shade progression is generally accomplished by means of a shade guide 18 such as shown in FIG. 1. A typical prior art shade guide 18 includes an elongated, linear holder 10 containing a plurality of specimens 12. Each of the specimens is comprised of a sample tooth 14 and a support member 16 for attaching the sample tooth to the holder 10. Each sample tooth 14 is provided with a predetermined shade and hue for matching with the patient's natural teeth. Shade guides are typically provided by manufacturers of prefabricated teeth for use as dentures, partials and implants over dentures. Crowns, bridges, laminates and veneers are, on the other hand, generally manufactured by dental laboratories using tooth powder materials (resins or porcelain) which have also been fabricated by tooth manufacturers.
The conventional prior art shade guide 18 such as shown in FIG. 1 includes an average of twelve shade selections fixedly mounted in sequence on the common holder 10. The dentist must match one of these shades to the shade of existing teeth in the patient's mouth. If the patient is edentulous, the dentist, together with the patient, typically selects a hue and shade progression according to the age of the patient based upon the dentist's experience with the patient's approval. Once a hue and shade progression are selected, the doctor records the shade numbers and/or brand of teeth or material on a prescription. The prescription together with the patient's impression, which is usually comprised of hydrocolloid, silicone, alginate or rubber base, are sent to a laboratory for fabrication of a dental appliance. The laboratory set-up man or master technician selects the teeth for dentures, partials or implant over dentures, or the tooth materials for crowns, bridges, laminates or veneers by matching the shade number provided by the dentist in the prescription.
Although in widespread use, this approach is not error-proof, nor does it guarantee a perfect match for several reasons. For example, the shade guide used by the dentist is not the same as that used by the laboratory. The shade and hue of the materials used in a shade guide change with time, e.g., color intensity is reduced and colors tend to lighten, or fade, over time. This is particularly true where the shade guide is overexposed to sunlight or frequently disinfected, or sterilized, resulting in a change in the original tones. In addition, the doctor or fabricating technician may misread the color number on the shade guide or the shade guide manufacturer may erroneously identify the shade of one or more specimens in the shade guide. Finally, the tooth manufacturer may slightly change the shades of teeth or tooth powder in its production batches because of changes, which frequently depend on availability, of one or more ingredients. The occurrence of any of these events will result in an inaccurate matching of artificial teeth shade with the shade of natural teeth because the technician normally does not have access to the patient and was not present at the initial shade selection by the dentist.
While most mechanical problems with dental appliances can be corrected at chair side, the problems of shade matching discussed above cannot generally be thus corrected and typically require a return of the dental appliance to the denture manufacturer or lab resulting in patient inconvenience and dentist loss of labor time.
The present invention addresses the aforementioned problems of the prior art by providing an improved dental tooth shade matching reference system which provides the dentist as well as the tooth fabricating technician with a specimen precisely matched in shade and hue with the patient's natural teeth. Patient identifying labels are provided on both the dentist's and technician's specimens to eliminate the possibility of identification errors. This arrangement ensures that the patient's reference shade and hue are precisely known (1) at the time of patient examination by the dentist, (2) when the artificial tooth is fabricated, and (3) when the dental appliance is delivered to the dentist for installation in a patient.